The conventional CNC central cutting machine, as shown in FIG. 1, includes a main machine whose left side of the top thereof has a holder 2, which can turn and is circular, mounted thereon for fixing an object to be cut. The top of the machine 1 tilts down from back to head and also has two sliding tracks 3 mounted thereon in a direction identical to the axial direction of the holder 2. The two sliding tracks 3 are jointly assembled with a sliding seat 4, which also tilts down from back to head, and the sliding seat 4 can slide along the sliding tracks 3 to move to the right side or left side. Further, the sliding seat 4 has a dovetail trough 5 mounted at the top thereof in a direction from back to head, and a cutter rear seat 6 is assembled in the dovetail trough 5 through the bottom thereof, so that the cutter rear seat 6 can move upward and downward along the dovetail trough 5. In addition, the cutter rear seat 6 has a cutter holder 7 mounted thereon in an axial direction and corresponding to the direction of the holder 2, wherein there are plural fixing holes 8 distributed on the circular and the longitudinal surfaces of the holder 7 for locking and fixing the object (not shown), so that when cutting, the holder 2 with the object can turns rapidly. Then, through upwardly and downwardly adjusting the position of the cutter rear seat 6, the cutter can correspond to the object, and through the dovetail trough 5 of the sliding seat 4 and the sliding tracks of the machine 1, the cutter rear seat 6 can gradually move toward the object, so that the cutter can cut or polish the surface of the object.
However, as cutting, the cutter only can provide one circle of cutting with a particular depth when the object turns once, so that the cutting speed is limited.
Consequently, the applicant keeps on carving unflaggingly through wholehearted experience and research to develop a CNC cutting machine, which can solve the inefficient problem in the prior art.